January 7, 2009
There are construction projects where only copper pipe will do. The ability to correctly sweat a copper pipe remains the test of a skilled plumber. And as long as there is copper pipe, plumbing professionals will have to master the use of solder and flux.
While there have been no dramatic changes in the composition of solder and flux in recent years, manufacturers say they are always striving to improve these products in terms of speed, performance and environmental concerns. We asked solder and flux manufacturers about the impact of legislation as well as new piping and joining methods on this product category.
On this month’s panel of industry professionals are: Harvey Wiseman, CEO of The Wiseman Group, makers of Everflux, Essex, England; Deborah Petrille, marketing manager, LA-CO Industries, Elk Grove, Ill., manufacturers of LA-CO flux and soldering products; Lee Wilkins, director of marketing, joining technologies, Lenox, East Longmeadow, Mass., producer of Sterling lead-free solder; and Eva Ackerman, vice president of technical services, Rector-Seal Corp., Houston, maker of the NOKORODE flux line.
RJ: What are the biggest changes we’ve seen in the composition of solder and flux?
Everflux: The introduction of the standard ASTM B813 led to a big change in flux composition. Its requirement for water-flushable flux led to the introduction of new fluxes to the market such as Everflux and other brands had to reformulate to meet the standard. Continued development of these fluxes over the past 10 years has meant that the range of temperatures under which the flux can work has been increased, making it easier to solder a completely leak-free installation.
LA-CO: The biggest changes have been the elimination of lead in solder and water soluble fluxes for potable water pipes. These changes came about due to the new plumbing codes and laws, which forced the manufacturers to change the composition of their solder and fluxes.
RectorSeal: The biggest change has been more environmentally friendly and less aggressive fluxes.
Lenox: There have been dramatic changes in solder composition over the the past 20- or 25 years with the passage of the Safe Drinking Water Act of 1986. This effectively eliminated the use of leaded solder in potable water applications and brought about new lead-free solder formulas. Companies have been working to duplicate the lower melting temperature and flow characteristics of leaded solder over this time period. Lead-free solder formulas used today vary greatly with the use of different alloys to try and maximize joint strength, workability, and lower melting temperatures.
The other big change over the past few years is the creation of water-soluble lead-free flux that meets the ASTM B-813 specifications for solubility in potable water applications. The advantage of water-soluble flux is the fact it can be flushed from a new or repaired potable water system by using water instead of the chemicals used for flushing petroleum-based flux. This saves time and cost on the job.
RJ: What drove the changes? Is legislation having an impact?
Everflux: The belief that “old-style” insoluble flux could cause long-term corrosion problems in copper led to the Copper Development Association developing the CDA 1 standard, which became the general basis for the ASTM B813 standard now enforced by inspectors nationwide. The result of this legislation is that pin holing in copper does not come from flux corrosion. This ultimately is a good thing for plumbers, meaning fewer callbacks and, ultimately, fewer leaks and a better reputation.
LA-CO: The hazardous effects of lead warranted the elimination of lead in all of these products.
RectorSeal: Major model building codes requirements. It was a joint effort of CDA, ASTM and flux manufacturing companies to develop ASTM B813 standard which limits the corrosivity of soldering fluxes and ensures that these fluxes are flushable in cold water, which makes easy to remove flux residues after installation.
Lenox: The primary drivers of this change are stated above. Also, NSF 61 certification and the ASTM B-813 specification is being adopted as code by more and more state and local municipalities to determine which products can be used in potable water applications. Those products and manufacturers that are certified under NSF 61 and meet ASTM B-813 specifications will have, and currently do have, a leg up in providing safe, certified products under these guidelines.
RJ: What’s new in the solder and flux market?
Everflux: Through ongoing development, the major flux manufacturers aim to produce a quicker, better, safer, more environmentally sound product. The very latest formulation of Everflux is a very low-fuming product which has got to be good for all those working with flux every day.
LA-CO: There is really is not anything new in the solder and flux market, but there are heat barrier sprays, like Cool Gel. Heat barrier sprays are used by plumbers to protect the previously soldered joints and surrounding components and materials from heat and fire damage. Fire damage is too great a risk in today’s legal environment. A plumber needs to protect the job, the customer and the company.
RectorSeal: What’s new is that the new fluxes are environmentally friendly, but the performance is not compromised; the new fluxes are environmentally friendly, but the performance is not compromised.
Lenox: Since 1996, many code jurisdictions are requiring the use of water-soluble flux. Some states such as California, Minnesota, Wisconsin and others have passed very restrictive codes (ASTM B813) that limit the use of petroleum-based paste flux in potable water applications. Water-soluble flux is less corrosive to the installer and the plumbing system. Petroleum fluxes commonly contain 40 percent chloride. Water soluble flux contains less than 5 percent. The chloride in petroleum flux remains present in the plumbing system and on the installer until thoroughly cleaned with a chemical solution. Water-soluble residues are easily removed with plain water.
RJ: What’s the key to the proper use of solder and flux?
Everflux: The key to the best joint is not to overheat the joint. The role of a flux is both to prepare the surface for soldering and aid the introduction of solder throughout the joint. A flux like Everflux removes the buildup of oxides in the microscopic valleys of the copper, giving the solder a better surface on which to adhere. When the solder is applied to the joint, the hot flux generates a capillary effect to draw the solder throughout the joint.
LA-CO: The key to properly using solder and flux is not to over-heat the joint. Overheating the joint will cause the flux to burn off before the solder is applied, leaving gaps in the joint potentially causing leaks. To prevent flux burn off, heat the joint evenly and this will also promote the best solder flow.
RectorSeal: The key to use of solder and flux is properly following the manufacturer’s instructions and good workmanship.
Lenox: A neat and correctly soldered or sweated joint is the mark of a true master tradesman. To avoid the common errors in soldering copper pipe, make sure you follow the proper preparation and sweating techniques for a solid joint found in the ASTM B-828 procedure.
Flux has two primary purposes in the preparation of the pipe and fitting. Flux further cleans and etches the metal and helps the solder flow properly and fill voids for a tight connection.
RJ: How is working with water-soluble flux different?
Lenox: Petroleum and water soluble lead-free flux are the two most common types of flux used in potable water applications. Water-soluble flux is best used with a lead-free solder that melts at a relatively low melting temperature. It is also important not to overheat the work. This can cause pitting and can reduce the effectiveness of the flux. Overheating can cause flux to boil and evaporate at a faster rate reducing the chance for a properly sweated joint.
The working difference between using water soluble lead-free flux and petroleum paste flux is the temperature zone of operation. Water-soluble flux evaporates at approximately 600 degrees Fahrenheit. Petroleum-based paste flux evaporates at approximately 800 F. Lead-free solder has a working temperature range between 410- and 640 F. Caution should be used to prevent overheating when using water-soluble flux.
Most plumbers were trained using petroleum-based flux and solder. They were taught to use sight and sound. After the heat is applied to the joint, the plumber should watch for the paste flux to “boil” and begin “popping and spitting.” When they see and hear this action, it is time to run the solder into the joint. Water-soluble flux operates in a smaller and lower temperature range than petroleum-based flux, so sight and sound won’t work as well.
Water soluble flux boils very quickly when heated rapidly. It doesn’t “pop and spit” like paste flux. If you wait to watch it bubble or hear it pop or spit, you’ll miss the working zone. It will have boiled off the pipe and the solder will not flow properly. After a short period of heat application to the joint you must begin touching the solder to the joint to determine if it has reached a sufficient temperature for the solder to flow into the joint. At this point you would remove the heat source so that the water soluble flux is not boiled away. To determine if the solder is ready to flow, use the touch method rather than the sight and sound method. This will allow completion of a leak-proof joint.